Process for degreasing wool and recovery of wool grease



United States Patent PROCESS FOR DEGREASING WOOL AND RECOVERY OF WOOL GREASE No Drawing. Application March 4, 1952,

Serial No. 274,820

7 Claims. (Cl. 260--412.8)

The present invention relates to the degreasing of wool and the refining of the wool grease so obtained,

and more particularly to a solvent extraction process of this character and to the processing of mixtures of wool grease, solvent, water and the usual contaminants present in raw wool grease to recover a refined wool grease therefrom.

It is well known in the art that in scouring wool, either with aqueous soap solutions or with organic solvents, it is necessary to use more than one scouring liquid to remove both the grease and the suint constituents as well as ordinary dirt. In the case of aqueous scouring, it is necessary to rinse out the soap or detergent solutions with plain water, while in the case of all rior solvent scouring processes it has been necessary to use either a plurality of organic solvents, such as methyl alcohol followed by ethyl alcohol, or to follow the organic liquid scour with an aqueous scour.

An object of my invention is to provide an improved process for removing from raw wool not only the grease but also the suint and the dirt by a single liquid treatment with a single solvent, to prepare the wool for textile uses and to provide the grease in a readily recoverable form.

A further object is to provide a process for the solvent scouring of raw wool in which the suint can be completely removed while, if desired, leaving a controlled amount of grease on the wool.

A further object is to provide improved and simplified recovery processes for recovering wool grease from mixtures of wool grease, water and the contaminants usually associated with raw wool.

A further object of my invention is to provide such recovery processes in which a high quality of wool grease, or lanolin, is obtained.

A further object is to provide a wool grease recovery process which will give a minimum of stream pollution from the wastes when discharged into the stream.

According to my invention the raw wool is scoured with methylene chloride [CH2C12] in any suitable way, and my invention is not confined to any particular extraction procedure. I have found that by scouring the wool with methylene chloride I can remove all the suint from the wool as well as all the grease, and further I have found that the rate of removal of the suint is much greater than the rate of removal of the grease, so that it is readily possible to stop the grease removal before it is complete without running any risk of leaving in the wool any of the undesired suint. It is, of course, entirely practical to remove all the gerase with methylene chloride, so that it is not necessary to leave any grease on the wool unless it is so desired. The methylene chloride used in my process is non-flammable, which is highly advantageous.

Most wool processed today is of the so-called alkalidamaged type, and it is customary to treat solvent-scoured wool with alkaline solutions after scouring to produce wool of this type. In the case oi:' my invention such 2,723,281 Patented Nov. 8, 1955 alkali-damaged wool may be attained by using methylene chloride saturated with an aqueous alkali. Due to the relatively high solubility of water and aqueous solutions in methylene chloride as compared with other chlorohydrocarbons, suflicient alkali, such as sodium carbonate, can be dissolved and will remain in a suificiently ionized condition to produce alkali-damaged wool without the need of a separate treatment.

The following example illustrates the use of my invention to produce clean, scoured wool with a single solvent:

Four pounds of a commercial blend of fine Australian wool containing 14% moisture, 16.25% grease, 7.94% suint after the grease extraction, and 3.35% potassium, was extracted five times in a batch-type extractor with six times its weight of methylene chloride. The extractor was filled with wool, the solvent was run into the extractor and was allowed to remain quietly in contact with the wool, and was then drained OE, and fresh solvent was run in. After the fifth extraction, the wool was removed from the extractor and was dried in an oven at C. The following constants were determined on the various extracts:

Percent Percent Extraction No. Solids Potassium Extracted Extracted Total 22. 14 3. 34

(all figures are computed on the grease wool basis) Analysis of the final extracted wool showed that 2.0% grease remained on it. The sum of the solids extracted from the wool plus the residual grease equals 24.14%, whereas initially the sum of the grease plus water extractables was 24.19%. Approximately 2.0% grease was left on the wool while simultaneously all the suint was removed, as is indicated by the fact that all the potassium originally present in the wool was completely removed. Thisrfact was confirmed by an analysis of the scoured wool, which showed it to be potassium free.

The extracted wool was clean, soft, light colored, lofty, free of any sticky feeling, of good scroop and hand, and was suitable and ready for all the further textile operations usual for scoured wool.

The miscellas obtained in the above extraction were each washed twice with an equal volume of water, each time with violent agitation. The resultant miscellas surprisingly did not form stable emulsions but broke readily, and the solvent layer and the aqueous layers were separated by decantation of the latter. Analysis of the aqueous washings yielded the following data:

First Washing Second Washing From Miscella No. P P

ercent ercent Percent Percent K Grease Grease Totals 1. 89 0. 40 0.67 0.530 0. 04 0.29

These data show that the suint is eifectively removed from the miscella by water Washing, and that the B. O. D. (biological oxygen demand) of the efiiuent Water is very low per pound of grease wool.

In practice, where the total volume, of water involved is relatively small, it would be economical to recover the suint salts from the wash water and to use them as a source of chemicals such as fatty acids, or to burn them and recover potassium carbonate by conventional and well known processes thereby further reducing the B. O. D. of the waste. It is therefore possible in my process to discharge the waste into a stream with little or no pollution problem. This is a very important advantage since in all other wool scouring processes the amount of polluting material which must be discharged to streams constitutes a serious pollution problem and requires very expensive installations to reduce the total eilluent B. O. D. to acceptable proportions.

The water washed miscella can now be readily filtered. These miscella, containing wool grease and methylene chloride which have been water washed and then separated from the water containing the water-soluble contaminants, can, I have found, be further purified by passing them through an adsorption column containing, for

example, activated carbon, activated silica gel or activated clay for the removal from the grease of organic impurities capable of being removed by adsorption, particularly and importantly color-forming impurities. In solvent grease extraction processes heretofore known so far as I am aware, the distillation operation for. removal of the solvent has been performed on the extract containing such color-forming ingredients, resulting in serious discoloration of the grease product by polymerization or other change in those ingredients at the necessarily high temperatures of the distillation step. For this reason, wool grease obtained from the solvent-extraction type of wool degreasing process has been notorious for its low quality as respects color. For many uses of the grease, e. g. for cosmetic purposes, color is a primary consideration in determining the quality and value of the grease. in my processes such discoloration is avoided.

It is also possible, although by no means necessary, to neutralize at this stage the free fatty acids naturally present in wool grease and to wash out the resultant soaps with water.

Whether or not the free fatty acids are neutralized, the solvent may be readily evaporated to leave behind the purified grease components. Because of the low boiling point of methylene chloride (40 0.), it is readily possible to distill the solvent away fromthe grease without subjecting the labile grease components to a temperature sufficient to oxidize, polymerize, or otherwise degrade them, thus avoiding the formation of any off-color or malodorous compound. A further advantage accruing from the use of methylene chloride is the fact that it is possible to remove the solvent from the miscella at room temperature without supplying any heat, simply by reducing the pressure in the still-pot or container. No great pressure reduction is required, that provided by a simple steam or water jet evactor being ample to accomplish my purpose.

The scouring process may be carried out in equipment which first brings the raw grease wool in contact with the methylene chloride, then separates the methylene chloride from the wool, and finally dries the wool. The entire process may be carried out in a vapor tight shell, from which the evaporated methylene chloride may be recovered. There are innumerable variants of such equipment commercially available, and I wish it understood that my process is not restricted to any one particular machine or type of machine but may successfully be operated with any type of scouring machinery, although I prefer for economic reasons that the process be practiced entirely in wholly enclosed equipment from which the volatilized methylene chloride may be recovered. Suitable equipment which is available commercially has been described in detail in U. S. Patent 2,368,916 (Drum et 211.), as well as many older patents, such as 899,440 (Shuman). It is to be understood that my invention is not restricted to such continuous scouring equipment but may be readily carried out in batch or discontinuous-type equipment.

My process is applicable also to the recovery of high quality wool grease from mixtures of such grease with Water, water-soluble and water-insoluble contaminants. Thus wool grease may be recovered from the wool scouring liquor resulting from the conventional aqueous wool scouring operation employing a scouring bath of water, soap and alkalis by adding methylene chloride to the scouring liquor and then employing the recovery procedures described above.

I claim:

1. The process for the recovery of wool grease from raw wool which comprises leaching the raw wool containing wool grease and suint with methylene chloride to extract wool grease and suint therefrom, separating the liquid extract from the wool fibers, washing the extract with water, and separating the aqueous phase containing suint from the non-aqueous phase containing wool grease.

2. The process for the recovery of wool grease from raw wool which comprises leaching the raw wool containing wool grease and suint with methylene chloride to extract wool grease and suint therefrom, separating the liquid extract from the wool fibers, washing the liquid extract with water, separating the aqueous phase contain ing suint by sedimentation, and removing methylene chloride from the remaining grease-rich portion of distillation.

3.. The process for the recovery of wool grease from raw wool which comprises leaching the raw wool containing wool grease and suint with methylene chloride to extract wool grease and suint therefrom, separating the liquid extract from the wool fibers, mixing water with the liquid extract and agitating the mixture to leach suint from the extract, separating from the extract by sedimentation the resulting aqueous phase containing suint, and removing methylene chloride from the remaining extract by distillation.

4. The process for the scouring of raw wool and the purification and recovery of the wool grease which comprises leaching the raw wool containing wool grease and suint with methylene chloride to extract wool grease and suint therefrom, separating the liquid extract from the wool fibers, mixing water with the liquid extract and agitating the mixture to leach suint from the extract, separating from the extract by sedimentation the resulting aqueous phase containing suint, removing organic color-forming materials from the remaining extract by contacting the extract with an adsorption medium for such materials, and removing methylene chloride from the remaining extract by distillation at room temperature.

5. Theprocess for the recovery of wool grease from raw wool which comprises leaching the raw wool containing. wool grease and suint with methylene chloride to extract wool grease and suint therefrom, separating the liquid extract from the wool fibers, mixing Water with the liquid extract and agitating the mixture to leach suint from the extract, separating from the extract by sedimentation the resulting aqueous phase containing suint, neutralizing free fatty acids in the remaining extract, washing the extract with water to remove the so formed soaps, and removingmethylene chloride from the remaining. extract by distillation.

6. The process for the recovery of wool grease from a mixture of wool grease, water, and raw wool grease contaminants, which comprises extracting wool grease and suint from said mixture with methylene chloride, mixing. water with the extract and agitating it to leach suint therefrom, separating by sedimentation the resulting aqueous phase containing suint, and removing methylene chloride from the remaining grease-rich portion by distillation.

7. The process for the recovery of wool grease from a mixture of wool grease, water, andraw-wool-grease contaminants, which comprises extracting grease and suint from said mixtures with methylene chloride, mixing water With said extract and agitating the mixture to leach suint from the wool grease, separating by sedimentation the resulting aqueous phase containing suint, removing organic color-forming materials from the remainder of the mixture by contacting it with an adsorption medium for such materials, and removing methylene chloride from the remaining wool grease by distillation.

References Cited in the file of this patent UNITED STATES PATENTS 1,636,351 Beil et a1. July 19, 1927 Gillespie OTHER REFERENCES Wool Wax (1948) pages 22-25. 

1. THE PROCESS FOR THE RECOVERY OFWOOL GREASE FROM RAW WOOL WHICH COMPRISES LEACHING THE RAW WOOL CONTAINING WOOL GREASE AND SUINT WITH METHYLENE CHLORIDE TO EXTRACT WOOL GREASE AND SUINT THEREFROM, SEPARATING THE LIQUID EXTRACT FROM THE WOOL FIBERS, WASHING THE EXTRACT WITH WATER, AND SEPARATING THE AQUEOUS PHASE CONTAINING SUINT FROM THE NON-AQUEOUS PHASE CONTAINING WOOL GREASE. 